diff --git a/src/cmserr.c b/src/cmserr.c
index ac89811a..78a5acd8 100644
--- a/src/cmserr.c
+++ b/src/cmserr.c
@@ -590,6 +590,7 @@ static
 void* defMtxCreate(cmsContext id)
 {
     _cmsMutex* ptr_mutex = (_cmsMutex*) _cmsMalloc(id, sizeof(_cmsMutex));
+    if (ptr_mutex == NULL) return NULL;
     _cmsInitMutexPrimitive(ptr_mutex);
     return (void*) ptr_mutex;   
 }
@@ -680,7 +681,7 @@ void CMSEXPORT _cmsDestroyMutex(cmsContext ContextID, void* mtx)
 {
     _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);
 
-    if (ptr ->DestroyMutexPtr != NULL) {
+    if (ptr ->DestroyMutexPtr != NULL && mtx != NULL) {
 
         ptr ->DestroyMutexPtr(ContextID, mtx);
     }
@@ -690,7 +691,7 @@ cmsBool CMSEXPORT _cmsLockMutex(cmsContext ContextID, void* mtx)
 {
     _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);
 
-    if (ptr ->LockMutexPtr == NULL) return TRUE;
+    if (ptr ->LockMutexPtr == NULL || mtx == NULL) return TRUE;
 
     return ptr ->LockMutexPtr(ContextID, mtx);
 }
@@ -699,7 +700,7 @@ void CMSEXPORT _cmsUnlockMutex(cmsContext ContextID, void* mtx)
 {
     _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);
 
-    if (ptr ->UnlockMutexPtr != NULL) {
+    if (ptr ->UnlockMutexPtr != NULL && mtx != NULL) {
 
         ptr ->UnlockMutexPtr(ContextID, mtx);
     }